1. Field of the Invention
This invention relates to a substrate treating apparatus and a substrate treating method in which a substrate having a very small thickness such as a semiconductor substrate and a glass substrate for use in a liquid crystal display panel (hereinafter, merely referred to as a xe2x80x9csubstratexe2x80x9d) is immersed in a treating liquid such as a chemical liquid and de-ionized water (or refined water) filled in a treating bath to apply a certain treatment onto the substrate.
2. Description of the Background Art
There have conventionally been conducted various surface treatments in which a substrate is immersed in a treating liquid in a process of producing a substrate for use in a precision electronic device. One of known substrate treating apparatus comprises a chemical bath filled with a chemical liquid such as etchant and photoresist film peeling liquid and a water bath filled with de-ionized water (or refined water).
More specifically, after a substrate is immersed in a chemical liquid in the chemical bath to apply a chemical treatment onto the substrate, then, the substrate is immersed in de-ionized water in the water bath to wash away the chemical liquid adhered to the substrate and particles generated and adhered to the substrate during the chemical treatment.
One method of washing off the chemical liquid and the particles is a mechanical rinsing treatment according to which the chemical liquid and the particles are quickly rinsed off. Hereafter, the mechanical rinsing treatment is described with reference to FIGS. 1A to 2.
FIGS. 1A to 1E are diagrams showing a sequence of the mechanical rinsing treatment in a mechanical rinsing section of the conventional substrate treating apparatus. Specifically, FIG. 1A shows a state that a substrate applied with a chemical liquid has been transported to the mechanical rinsing section and is about to be immersed in de-ionized water in the water bath. FIG. 1B shows a state that the substrate has been immersed in the de-ionized water in the water bath, and the water bath is resultantly brought to an overflow state. FIG. 1C shows a state that a high speed drainage is performed spontaneously with actuation of a shower. FIG. 1D shows a state that the high speed drainage is suspended and the water bath is being replenished with de-ionized water with continuation of the shower. FIG. 1E shows a state that the water bath is brought to an overflow state again.
As shown in FIG. 1A, a group of semiconductor substrates 53 (hereinafter, merely referred to as xe2x80x9ca substrate groupxe2x80x9d and in FIGS. 1A to 1E, only one substrate is shown) held by a transport robot (not shown) is transferred from a chemical bath 52 to a water bath 51 and handed to a lifter 55 provided in a mechanical rinsing section 50. When the substrate group is handed to the lifter 55, the substrate group is held by a three-point support guide 54 at lower portions thereof in a state that all the substrates are held in an upright posture at a specified interval (e.g., normal pitch P=6.00 mm or half pitch {fraction (P/2+L )}). In this state, the substrate group is immersed together with the support guide 54 in de-ionized water filled in the water bath 51 (see FIG. 1B).
At this stage, de-ionized water is continued to be replenished through water supply portions 56 provided at opposite ends of a bottom portion of the water bath 51. When the substrate group is immersed with the support guide 54 in the water bath 51 with the continued replenishment of de-ionized water, the de-ionized water in the water bath 51 overflows from an upper rim 51a of the water bath 51. Thus, the chemical liquid adhered to the substrate group and particles generated and adhered to the substrate group during the chemical treatment are washed away together with the overflowing water from the water bath 51.
After continuation of the overflow state for a predetermined time, as shown in FIG. 1C, replenishment of de-ionized water through the water supply portions 56 is temporarily suspended in the case that the surface of the substrate group exhibits a hydrophillic state. Simultaneously, a drainage valve 57 provided at a lower portion of a side wall of the water bath 51 is opened to drain the de-ionized water mixed with the chemical liquid and the particles from the water bath 51 at a high speed. At the same time as the opening of the drainage valve 57 or after a duration of a certain time (before the substrate group is being exposed to the air owning to the high speed drainage), a nozzle (not shown) of each of shower pipes 58 provided opposingly above the upper rim 51a is operated to shower de-ionized water onto an upper portion of the surface of the substrate group. In this way, the surface of the substrate group is prevented from being exposed to the air, thereby suppressing deposition of an oxide film on the surface of the substrate group, which might have caused naturally due to exposure to the air.
Upon completion of the high speed drainage in a state that the shower of de-ionized water through the nozzles of the shower pipes 58 is continued, as shown in FIG. 1D, the drainage valve 57 is closed, and replenishment of de-ionized water through the water supply portions 56 starts. Thereby, the water bath 51 is filled with de-ionized water again, and thus, water replacement in the water bath 51 is performed.
The replenishment of de-ionized water through the water supply portions 56 is continued (see FIG. 1D). Consequently, as shown in FIG. 1E, the de-ionized water in the water bath 51 overflows from the upper rim 51a of the water bath 51 again to wash off the chemical liquid and the particles adhered to the substrate group 53 along with the overflowing water.
The above sequence is executed in accordance with the timing shown in FIG. 2. Specifically, as shown in FIG. 2, the following operations are executed at timings T1, T2, T3.
T1: Suspend supply of de-ionized water through the water supply portions 56;
Start shower of de-ionized water through the nozzles of the shower pipes 58; and high speed drainage starts by opening the drainage valve 57.
T2: Start replenishment of de-ionized water through the water supply portions 56; and
Suspend the high speed drainage by closing the drainage valve 57 (at this time, the shower continues).
T3: Suspend shower (at this time, the replenishment of purified water through the water supply portions 56 continues, and the drainage valve 57 is kept closed).
The above sequence is cyclically repeated for a predetermined number of times. Thus, the chemical liquid and the particles adhered to the substrate group are removed therefrom.
The conventional arrangement of holding the substrate group by the lifter 55 has suffered from the following problem. As shown in FIG. 3A, each substrate 53 is supported in each of support grooves 54a formed in the support guide 54. Specifically, lower ends 53a of the substrates 53 are detachably fitted in the support grooves 54a of the support guide 54 at a specified interval, thereby restricting a movement of the lower portions of the substrates 53. Thereby, the substrate group is supported in an upright posture at three lower portions thereof by the support guide 54. However, an upper portion of the substrates 53 is set free without any support. Accordingly, what happens at the high speed drainage is an undesired contact of the adjacent substrates 53 as shown in FIG. 3B due to a turbulence of the water flow in the water bath 51.
More specifically, at the start of the high speed drainage, accompanied with a drastic lowering of water surface 61 (or liquid level 61 in FIG. 3B) of the de-ionized water in the water bath 51 along with a gush of the de-ionized water drawn out through the drainage valve 57, a turbulence or a swirling occurs in the de-ionized water in the water bath 51. Thereby, the upper portion of the adjacent substrates 53 is tilted to each other about the support portion 53a fitted in the support groove 54a, as shown in FIG. 3B, and the upper portion of the surface of the adjacent substrates 53 comes into contact to each other.
In particular, when the surface of the substrate 53 exhibits a hydrophillic state, it is highly likely that the substrates 53 may come into contact in a state that water on the surface of the substrates 53 remains in between. Accordingly, it may be difficult to detach the adjacent substrates 53 in contact, and a forcible detachment of the substrates 53 may result in a damage or a breakage of the substrate(s) 53. In addition, the undesired contact of the substrates 53 may generate particles and transmit the particles adhered on one substrate to the adjacent substrate in contact. The last problem is significant particularly in the case where the substrate group is held at a small interval (e.g., half pitch {fraction (P/2+L )}).
There is proposed an idea to avoid the above undesired contact of the substrates 53 that the support groove 54a of the support guide 54 is formed into a V-shape with an attempt to securely hold the lower part 53a of the substrates 53. In this case, however, the secured retaining of the lower part 53a of the substrates 53 impairs flexibility of the substrate itself, although the upper part of the substrates 53 is set free. Specifically, when a turbulence or a swirling happens in the water flow accompanied with a drastic lowering of the liquid level 61 due to a high speed drainage in a state that the lower part 53a of the substrates 53 is trapped in the V-shaped support groove, the free upper portion of the substrates 53 is strongly pushed into each other, and the entirety of the substrate 53 is tilted to each other about the tightly held lower part 53a in the V-shaped groove. As a result, there may be a high possibility of a crack in the substrate 53, and in a worse case, a breakage of the substrate 53.
There is proposed another idea of providing a support guide formed with grooves in the water bath 51 to securely hold a substrate group in the water bath 51, thus preventing tilting and adhesion of the substrates 53. However, this idea requires extra support guide, which would become an additional element in the water bath 51. Further, positioning the support guide 54 relative to the fixed support guide in the water bath 51 is difficult. Also, the fixed support guide in the water bath 51 obstructs smooth water flow in the water bath 51, thereby deterring water replacement in the water bath 51.
In view of the above, it is an object of the invention to solve the above drawbacks residing in the prior art.
It is another object of the invention to provide a substrate treating apparatus and a substrate treating method capable of preventing tilting and adhesion of adjacent substrates during a high speed drainage to prevent damage of the substrates, generation of particles, and adhesion of the particles to the substrates without providing an additional support guide formed with grooves.
In order to fulfill the above objects, a substrate treating apparatus, according to an aspect of this invention, in which substrates are immersed in a treating liquid filled in a treating bath to apply a certain treatment to the substrates comprises a drainage system for draining the treating liquid from the treating bath; and a controller for setting a relative positional relationship between the substrates and the liquid level of the treating liquid to expose part of the substrates above the liquid level of the treating liquid prior to a high speed drainage by the drainage system.
According to-another aspect of this invention, this invention relates to a substrate treating method comprising the steps in the order of: a treating process of applying a certain treatment to substrates by immersing the entirety of the substrates in a treating liquid filled in a treating bath; a position adjusting process of setting a relative positional relationship between the substrates and the liquid level of the treating liquid to expose part of the substrates above the liquid level of the treating liquid; and a high speed draining process of draining the treating liquid from the treating bath at a high speed.